1. Field of the Invention
The present invention relates to a digital communication method and device using the method, and more particularly to a method of channel coding in which a Hamming distance between a pair of channel codes appropriately changes and digital data without source coding is channel coded, and a channel coding device using the same.
2. Description of Related Art
When sending a parcel, a weight of a parcel should be as light as possible in order to reduce the shipping cost. In order to reduce the shipping cost of the parcel, eliminating extraneous contents of the parcel are required, and source coding in a digital communication is analogous to a process of eliminating extraneous contents in sending a parcel. Once extraneous contents are eliminated in a parcel to be sent, a proper package for the parcel is required in order to protect the parcel from rough handling and damage. Similarly, channel coding in a digital communication is analogous to a process of properly packaging the parcel to be sent. However, channel coding is slightly different from sending a parcel in proper packaging to protect contents from damage in that, even though data of contents may be destroyed during operation of channel coding, an error detection or an error correction may be possible in the digital communication.
Channel coding in a digital communication is a method of adding data to the original data in the data transmission, so that error caused by noise in a channel may be detected and corrected by a receiver, and the channel coding is called ECC (error control coding). In ordinary channel coding, an ability for error detection or error correction is acquired by adding some bits to the original data which is generally said to be a message. The primary concern in channel coding is recovering from an inevitable error occurring in a channel by adding a few bits.
Normally, when channel coding, a channel space is created to have a similar Hamming distance between a pair of channel codes. In this instance, a Hamming distance corresponds to a number of different bits. As an example, a Hamming distance between “00100101” and “00000000” is three and a Hamming distance “11111111” and “00000000” is eight.
Since a wireless ear set utilized for transmitting and receiving multimedia data, such as music and the like, should be lightweight and easy to carry, a source decoder having a complex configuration may not be equipped in a wireless ear set. Accordingly when multimedia data is transmitted and received in a wireless ear set, a source coding is not normally utilized. Namely, since a wireless ear set transmits multimedia data without source coding, source decoding may not be required for a wireless ear set of receiver, and a complicated source decoder may not be required. In digital data which has not been channel coded, information significance per bit may differ, such as an MSB (Most Significant Bit) and an LSB (Least Significant Bit). That is, in digital data which has not been channel coded, even if there is the same bit ‘1’, one ‘1’ bit may correspond to a larger analog value and another ‘1’ bit may correspond to a smaller analog value.
As described above, when a general method of channel coding is utilized while channel coding digital data which have an MSB and an LSB, Hamming distances between a pair of the channel codes may be very similar, so that, despite significance of a corresponding bit, a bit error occurs during a transmitting operation via a channel.
Accordingly, when digital wireless communication in which source coding is omitted is executed (e.g., such as when transmitting multimedia data via a wireless ear set) in channel coding, since each bit is important, a new method of channel coding which can reduce a bit error rate and a new device of channel coding is earnestly required.